A. Field of Invention
This invention relates to an antibiotic, a new composition of matter called rapamycin, and to a process for its preparation.
B. Description of Prior Art
The antibiotic of this invention is readily distinguished from prior art compounds of its class by its profound antifungal activity and its relatively low order of toxicity.
More explicitly, the ultra violet spectrum of rapamycin, noted herein, indicates that this compound belongs to the class of antibiotics known as triene antibiotics. In this particular class there are only five compounds reported previously, Trienine, A. Aszalos et al., J. Antibiotics, 21, 611 (1968) is a triene antibiotic with antitumor activity which also shows marked activity against gram positive organisms and only marginal activity against Candida strains. The antifungal triene reported by J. J. Armstrong, et al., Nature, 206, 399 (1965) and Mycotrienin reported by C. Coronelli et al., J. Antibiotics, 20, 329 (1967) are probably identical. Both have low antifungal activity (MIC against C. albicans: 5 .mu.g/ml) and high toxicity (LD.sub.50 in mice: 15 mg/kg). The remaining two antibiotics - Resistaphylin, S. Aezaiva et al., J. Antibiotics, 14, 393 (1971) and Proticin, G. Nesemann et al., Naturwissenschaften, 59, 81 (1972)-are readily distinguished from the compound of the present invention in that they exhibit antibacterial without any antifungal activity.